I got some of those as a prize tournament many, many years ago. I don't know where they are anymore but they got a lot of use.
Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).
Must’ve been other ones (but probably similar) because these are apparently a new thing that a young Japanese woman created with help of some strong amateur player. On her FB page I saw a photo of very similar round coasters (w/o this wooden thing to stack them upon), perhaps she made those some time ago? Or this is where she got the idea from?
“The only difference between me and a madman is that I’m not mad.” — Salvador Dali
They look identical in form to the ones I had, but probably different problems.
Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).